Advice on sub placement and phasing with big SDA's

OldmanSRS

Looking for advice on where to place my HSU-VTF3 sub for best phase compensation with the SRS 1.2's. I have it crossed over a 25 htz. When adjusting the 0-180 phase switch, I notice a boost on the very low frequencies (16 -25 htz) at zero phase but with an attenuation in the 30 htz region. Running at 180* phase enforces the 30 htz region but attentuates the 16 - 25 htz region. I'm using a tone generator and various musical sources for the comparisons.

I suppose this uneven response is due to the interaction of the passive radiator on the Polks and the ports on the HSU. Standing waves are also a factor I think.

Are you guys placing the sub at the same end of the room as the SDA's or someplace else? Any advice is welcome.

Thanks,
Oldman

nooshinjohn

I hardly ever use a sub anymore with my 2.3Tl's... i suspect many here will say you do not need one if the SRS are properly set up. If you want to run a sub, I would get it set up as far away as possible from the SRS', perhaps behind the listening position. Mine is set up along side my sofa, but only kicks in if there is heavy action on-screen. It is used so rarely that I am thinking about getting rid of it all together.

eloo

Have you tried crossing over higher? Perhaps 40 htz.

bsoko2

I have a Conquest sub with my 2.3 TL's. The TL's are good but a good sub will really add to the HT experience for movies. Noosh, Play the "Irene" clip from Blackhawk Down with just the TL's and then with the sub. It sounds like you have your TL's set to large from your reciever and your sub only kicks in when the LFE is active. Try them small with the sub crossed at 80 hz. Now for 2-channel music, it is different for listening. Large is the way to go for the TL setup with the reciever and no to the sub setup.

Bill

artinaz

Its going to be pretty difficult to do it by ear. Best bet is to use the room eq wizard software and a radioshack meter and plot out the frequency response.

OldmanSRS

The SRS's are real good to about 25 htz. I listen to a lot of pipe organ and jazz. The HSU sub is real good down to 16 htz. It adds that sub bass octave and moves enough air to really make the system sound impressive at moderate listening levels.

I will use an oscilloscope and a mike to watch first the polks as I sweep from 35 htz to 16 htz and then add the sub checking which phase relationship provides the best sub-audio reinforcement and the least attenuation in the 25-35 htz region. I will move the sub around and see what affect that has on the standing waves.

I was hoping someone would chime in stating they have a similar setup and they place the sub next the polks or behind the listening area and run the sub at 0 or 180* phase shift.

BTW, I'm running 2ch mode with the LFE output active and large mode selected on the front speaksers in both 2ch and HT mode.

nooshinjohn

I still think getting the sub away from the SRS is the best solution. I would definately go with 180 out and behind teh listening area.

bsoko2

How low do the 2.3TL's go? When I run my SMS-1 it shows a roll off starting at about 60 to 55 hz. I have set my LFE crossover at 50 hz on the reciever and it has sounded like I have a big hole around 50 to 60 or so. Is this right?

Bill

Schurkey

bsoko2 wrote: »

How low do the 2.3TL's go? When I run my SMS-1 it shows a roll off starting at about 60 to 55 hz. I have set my LFE crossover at 50 hz on the reciever and it has sounded like I have a big hole around 50 to 60 or so. Is this right?

Bill

It's right if you're located in a standing-wave null zone.

BB3

nooshinjohn wrote: »

I still think getting the sub away from the SRS is the best solution. I would definately go with 180 out and behind teh listening area.

OldManSRS,

I'm with John on this. I keep both of my Velodyne's in the back of the listening area and they are placed in the rear corners of my room, which is still quite a bit away(7 feet or so) from my rear surround channel SDA-SRS 1.2TL's.

That being said, I feel the goal is to create a seamless operation between when the Sub comes into play or not. That of course is easier said than done without the proper tools at your side.

The last thing any of us as SDA owners would ever want to do is "muddy the waters" of the pristine sound of our speakers. You follow me ?

Take Care Of Yourself OldManSRS. I Sure Hope This Helps You Out

---

Bill(BB3)

ben62670

Set the XO point on the sub to 60 HZ max for music, and 80HZ for movies. You will want the sub set 180 out of phase because the PR's run 180 degrees out of phase. Also place the sub next to your SDA's for timing issues. Two subs makes a difference.
Ben

TNTsTunes

I'm working on a sub design to match my Yamaha RX-V3000 8.1 system. All of my speakers are Polks with passive radiators.

I'm designing a sub using a 15" Slaps passive radiator with 2.5" of excursion and a wicked 1200 watt RMS Konaki KO12-1207A 12" sub I have. The sub has a 3.0” voice coil, a 300 ounce magnet and 91db of sensitivity It will have 1200 watts of RMS power going to it. If that isn't enough sub for the passive radiator I also have a pair of Cadence 700 watt RMS subs I can use instead.

The sub will fire into a horn designed enclosure, but also have the forward firing Slaps passive radiator. This should help the phase issues and dig real deep.

TNTsTunes

I'll be building a folded horn type sub with about a 9' horn length. This should make the sound exit 180 degrees out of phase and in time with the passive radiator.

The Earthquake Slaps passive radiator I'm using is from a Earthquake SuperNova MKIV-15 subwoofer which is about a $2500-$3000 subwoofer.

My two 12" Cadence Wildbeast subs will go into some end table speaker that are from the 1970's I'm quessing. These I will wire 180 degrees out of phase.

My goal is to have all my bass in phase.

OldmanSRS

The best solution I came up with was to keep the sub in the right front corner of the room and run it 180* out of phase. I moved the XO point from 25 htz to 35 htz. The additional energy in the 30-40 htz range compensated for a deep 35 htz standing wave null located at the listenting position. I decreasesd the sub drive level by 3 dB. The improvement is huge with the bass tightenting and blossoming.

I also tried the sub behind the listening position but I could hear it. It worked well for HT where you want the focused energy but it was not transparent and seamless enough for music.

nooshinjohn

A sub should not be needed with the 1.2's for music. Perhaps there are placement issues with the SDA's that should be addressed...

OldmanSRS

I have a null at 35htz in the listening position. The sub fixes that. I can't move the speakers or the couch to compensate without compromising the SDA sweet spot.

I like really deep base in the 18-33 htz region. I listen at moderate levels 1-10 watts and the sub give me the low tactil bass the 1.2's just can't quite deliver in my room at the lower power levels. Some might just turn up the bass but I like tight response of the HSU sub.

eloo

Glad to hear about your improvement in bass. I run my SVS 20-39 in the left front corner with the XO at 40 htz.I prefer 0 phase shift as 180 increases bass but to my ears makes it a bit bloated and not as tight. My SDA-SRS speakers are along the same front wall with the left speaker about 3 feet from the sub. This setup allows my speakers to provide that wonderful SDA-SRS bass and the sub to supplement and reinforce the bass as it plummets into the subterranean.(Pardon the pun.)

thsmith

I do not have the big boys but I have their brother the 1Cs and a SVS PB13. No need for a sub with music. FOr HT the 1Cs and SVS play well together.

No matter the speaker subs need to be setup right.

Learn to use REW and all your problems will be solved.

Nice sub BTW. I had a VTF3-MK3.

OldmanSRS

What's REW?

Phil Dawson

In my system I have it set up so that the sub only gets information from the LFE channel. I mostly listen to music including multi channel SACD and DVD-A. Most music does not encode material for the LFE channel so my big boys get all of the low frequency information intended for each channel. I ran the system for a while without a sub but then the LFE channel material (in movies) was sent to all four of the big boys. This resulted in a lot more bass than was originally intended and it got kind of muddy.
Good Luck, Phil

eloo

Just a clarification.I do not run my sub with two channel music.The SDA-SRS system does not need it.The 40 htz XO referred to in my earlier post applies to home theater application only. The SDA-SRS system is set to LARGE.

thsmith

OldmanSRS wrote: »

What's REW?

Room EQ Wizard. S/W that runs on your PC, sound card and external mic. Creates graphs and let you see how your speakers are interacting and performing in your room, including phase.


S/W is free at hometheatershack.com , there is a learning curve but well worth it.

OldmanSRS

Phil Dawson wrote: »

This resulted in a lot more bass than was originally intended and it got kind of muddy.
Good Luck, Phil

Muddyness comes from the sub producing higher frequencies than about 30 htz and from distortion due to running it into it's power/excursion limits. The HSU VTF-3 is a VERY tight sounding sub with a very steep XO/enclosure design.

To clarify, I run the sub at very low volume. On pipe organ music at moderate levels (like in a church) it provides a subtle low end extension that sounds amazing. Turn it off and the SRS produce the 18-25 htz pipes but with the sub on it sounds like the room walls just became granite.

On jazz recordings the stand up base is tactil and the kick drum is tight and sweet. Or course if I drive the sub too loud the sound becomes unatural with base licks sounding like they came from a car stereo and kick drums that sound like explosions.

I have owned these speakers for 21 years and they have traveled the world with me. A good friend in Saudi owned the Infinity IRS Beta's and after listing to them, the SRS's were notabley weaker below 25 htz. Now my setup is nearly IRS-like at moderate levels.

Driver_King

You shouldn't ever be getting muddy bass with your HSU subwoofer. If you would like to remove all signs of muddiness or boominess, I would suggest building your own riser or purchasing an isolator. Corner placement sometimes can give you muddy bass. Have you done the subwoofer crawl before? That would help get you the best performance from your subwoofer. (If you're not familiar with the subwoofer crawl, it is where you place your subwoofer in your listening position and walk around the room to where the bass sounds the best. Then you simply place the subwoofer there.) I hope that helps!:)

OldmanSRS

Let me clarify. I'm not getting muddy base. I like what I'm hearing. That subwoofer crawl sounds like someting I want to try for fun. My system is located in a finsihed basement with a cement slab and block walls (finished with sheetrock).

Thanks for the suggestions.

Driver_King

OldmanSRS wrote: »

Let me clarify. I'm not getting muddy base. I like what I'm hearing. That subwoofer crawl sounds like someting I want to try for fun. My system is located in a finsihed basement with a cement slab and block walls (finished with sheetrock).

Thanks for the suggestions.

Your room is all the more reason to get it off the ground. A riser affects your subwoofer in a few ways: it can help decouple your subwoofer from the ground, it can improve the sound quality and output of your subwoofer, and it affects the axial room mode. The axial room mode is the vertical position of the subwoofer in a room. In a typical room with 8' ceilings, a 2' lift is ideal (either off the ground or hung off of the ceiling). It can be as or even more important than moving the subwoofer around in the room. Similarly, having multiple subwoofers can help drastically with evenness of bass across the room, helping eliminate dead spots and standing waves. Four subwoofers is ideal while two subwoofers is nearly ideal. You can read more subwoofer interaction here.

OldmanSRS

Thanks for the links. I have some reading to do.

thsmith

If you do not have bass traps and acoustic panals that might solve most of your problems. A subdude may help but traps and panals will do more for you.